My Perfect Roommate

DO NOT poop in my toilet! Grandma Geum-boon lives alone for life. Her roommate Ji-woong is a professional part-timer. A project to live with the senior who lives alone, which started to save some rent, repeats the difficulties and overcomes. Through that, they get close to each other. What will be the meaning of their room-sharing in this world with single-life hegemony?